Tag Archives: tobacco

Ebola virus currently has no licenced vaccine or cure, however several potential therapies are in development. Why does this merit mention on a blog about botany? For one good reason; scientists used plants in a bio-pharming approach to produce the potential Ebola treatment which was recently given to 3 patients infected with the virus. Bio-pharming uses genetic modification to introduce genes coding for pharmaceutical proteins (e.g. antibodies, or when produced in plants; ‘plantibodies’) into plants, the plant will then produce these proteins as if they were its own – essentially acting as a protein factory. The plants are harvested, the pharma-protein extracted and purified to a level comparable to any other medicinal protein.

Bio-pharming is currently in the news as ZMapp (Mapp Pharmaceuticals), an experimental antibody cocktail targeted against Ebola virus and produced in tobacco plants, was used in the treatment of two US aid workers and a priest infected with the virus. ZMapp is a combination of three antibodies which recognise different parts of Ebola glycoprotein; a protein present on the outside of the virus which allows the virus to attach to and enter into cells. The antibodies attach strongly to the Ebola glycoprotein thereby inactivating the virus, preventing it from entering cells and acting as a beacon to the patient’s immune system that the virus needs to be destroyed.Continue reading →

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Here’s a story that you should be hearing more about. It’s got monster-sized plants, eternal youth and a plant most people have heard of. The Fraunhofer Institute for Molecular Biology and Applied Ecology IME have put out a press release titled: “Giant tobacco plants that stay young forever“.

The secret of eternal youth isn’t found in an elixir. It’s found in flipping a genetic switch to prolong the youth of a tobacco plant.

Normally tobacco grows for a few months, flowers and then dies. What Professor Dirk Prüfer and his team have done is tweak a gene to stop the plant from flowering. If the plant never gets round to flowering then it never gets round to decaying either. This isn’t simply long life but also youth as well. There are knock on effects from this youth and this is what makes the research so interesting.

Typically, a tobacco plant grows to around one and a half metres. It can only grow so far because it has such a short life. However, if it stays young then it can also keep growing. In the press release Professor Dirk Prüfer said: “The first of our tobacco plants is now almost eight years old but it still just keeps on growing and growing. Although we regularly cut it, it’s six-and-a-half meters tall.” The release looks like it’s been embargoed, but it still catches the zeitgeist with what could be an #overlyhonestmethod when Dirk Prüfer added: “If our greenhouse were a bit higher, it would probably be even bigger.”

It’s this increase in biomass that makes the news interesting. It’s not going to lead to bigger cigars, but it could help with other agricultural produce. The current target is potatoes. In the case of potatoes more biomass will mean more production of starch. “If we want to guarantee security of supply for foodstuffs and plant-based raw materials, the yield per hectare will have to double by 2050, claims the German Bioeconomy Council. This new technology brings us a great deal nearer to that target,” said Prüfer. “However, our method is only likely to deliver success as long as the flowers of the plant in question play no significant role – sugar beet, for instance. It would make no sense to use the technique on rapeseed.”

Giant plants look like they could be a gift to both sides in the GM debate: will eternally young GM crops spread out into the wild? Not if they don’t flower say the Fraunhofer Institute, but they also say this isn’t the long-term goal. The current method uses bacteria transfer the genes. However, once this gene is understood the Fraunhofer Institute will look to achieve the same result by modifying the genes with chemical mutagenesis. The press release notes: “The advantage is that a plant grown in this way would no longer be genetically modified but simply a plant grown using standard techniques.”

This month’s winner in the ‘so simple it’s positively brilliant (but why did nobody think of it before?)’ category is Damar López-Arredondo and Luis Herrera-Estrella’s paper entitled, ‘Engineering phosphorous [sic.] metabolism in plants to produce a dual fertilization and weed control system’.

Apart from the unusual spelling of phosphorus in the title (it is correct in the body of the article – and this is important since the study deals with two similarly worded phosphorus compounds: phosphate and phosphite!), this is a most interesting piece of research. I can do no better than reproduce the paper’s own rather elegant summary of the work (from Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Guanajuato, México) here: ‘High crop yields depend on the continuous input of orthophosphate (PO43–)-based fertilizers and herbicides. Two major challenges for agriculture are that phosphorus is a nonrenewable resource and that weeds have developed broad herbicide resistance. One strategy to overcome both problems is to engineer plants to outcompete weeds and microorganisms for limiting resources, thereby reducing the requirement for both fertilizers and herbicides. Plants and most microorganisms are unable to metabolize phosphite (PO33–), so we developed a dual fertilization and weed control system by generating transgenic plants [arabidopsis and tobacco] that can use phosphite as a sole phosphorus source. Under greenhouse conditions, these transgenic plants require 30–50% less phosphorus input when fertilized with phosphite to achieve similar productivity to that obtained by the same plants using orthophosphate fertilizer and, when in competition with weeds, accumulate 2–10 times greater biomass than when fertilized with orthophosphate’. Or, and in summary, ‘the production of transgenic crop plants able to utilize phosphite, together with the application of phosphite as a source of phosphorus, might potentially become an effective phosphorus-fertilization and weed control scheme in the almost 67% of cultivated land with low ortho­phosphate availability’.

Whilst the authors are appropriately – and understandably – cautious about the significance of the results and how well they will scale-up to field-sized trials, this work – from the country whose CIMMYT (The International Maize and Wheat Improvement Center) was a major player in the Green Revolution of the last century – sounds like another agronomic development with tremendous potential. ¡Muchas gracias!

During their 2008–9 space odyssey the lichens were exposed to space vacuum (as low as 10–7 Pa), galactic cosmic radiation (£ 190 mGy), the full spectrum of solar radiation (l > 110 nm), and temperatures from –21.5 to 59.6 °C. Impressive? Yes, but even more impressive is the revelation by David Tepfer et al. that seeds of Arabidopsis thaliana and Nicotiana tabacum exposed to similar conditions also survived (for 558 days), with germination rates of 23 % and 44 %, respectively, back on the ground. In that latter study the authors concluded that ‘a naked, seed-like entity could have survived exposure to solar UV radiation during a hypothetical transfer from Mars to Earth’. I’m not sure if that means that it’s the Martians we must thank for the ‘gift of Arabidopsis’, or whether the return journey is also possible and that if we ever get to Mars at least the plant biologists will be able to continue to study their beloved thale cress (and tobacco – and maybe even lichens…)!

The water-transport capacity of leaf venation is positively related to the leaf-lamina area, because the number and diameter of vein-xylem conduits are properly controlled to match the lamina area. Taneda and Terashimainvestigate how these co-ordinated relationships are achieved by studying the midrib xylem of leaves of tobacco, Nicotiana tabacum, and find that the developmental rates of the lamina area and the midrib-xylem characteristics change in a co-ordinated manner. Exogenous application suggests that IAA derived from the leaf lamina plays a crucial role in the development of the leaf venation.

It must be terribly depressing if you don’t have plants in your life to give you purpose and a reason to get up in the morning, put digit to keyboard, or whatever. Still, for those who are intellectually botanically bereft, there is always one plant-derived stimulant or another to fill the void. And most of those in use have been exploited by man for a long time. But for how long have ‘we’ been using such phytological pick-me-ups as crutches to prop up our humdrum lives?

Well, a rather long time in the case of nicotine, according to work by Dmitri Zagorevski et al. Using GCMS (gas chromatography–mass spectrometry) and LCMS (liquid chromatography–mass spectrometry) they detected the presence of nicotine in a Late Mayan period flask (from approx. 700 AD/CE). Tellingly, clues to the former contents of the now-empty container were its inscription, which translates as ‘the home of its/his/her tobacco’. Still, in accordance with a true sceptical scientific approach, the flask’s residues were duly examined and the presence of nicotine (which addictive alkaloid is famously found in tobacco) was proved. Interestingly, if rather circularly, this independent hi-tech ‘proof of contents’ apparently constitutes only the second case to confirm that the text on the exterior of a Mayan vessel corresponds to its ancient use(!).

Presumably, this also represents evidence that even if you live in a supposed sub-tropical paradise like olden-days southern Mexico, you may still seek distraction and abstraction by indulging in the occasional bit of alkaloid abuse. And perhaps modern-day Mayans will choose to puff away on a cheroot as the world ends on 21st December 2012 (according to pessimism connected with the misunderstanding that the ancient Mayan calendar ‘runs out’ on that date), and – hopefully! – still be doing so on the 22nd of December, 2012 in relief that the world didn’t end… [This was written before the 21st December 2012. If you’re reading this item after that date, count yourselves lucky! – Ed.]

Not content with just being grateful for all of the marvellous things that plants do and provide, we humans always seem to want them to do even more. Well, in that vein there has been a veritable avalanche of stories that exploit the impressive chemical synthetic abilities of plants. Moran Farhi et al. have managed to persuade tobacco to manufacture artemisinin. Why? Artemisinin – and its derivatives – are a group of drugs that possess the most rapid action of all current drugs against Plasmodium falciparum malaria, a mosquito-borne infectious disease estimated to kill 2.23% of the world’s population according to the World Health Organization’s (WHO) 2011 World Malaria Report. Yes, but why in tobacco? Although artemisinin is isolated from its namesake Artemisia annua, low-cost artemisinin-based drugs are lacking because of the high cost of obtaining natural or even chemically synthesized artemisinin. Elsewhere, Xing Xu and colleagues have created recombinant human collagen in transgenic maize. But not only that, they importantly demonstrate that such a ‘system’ has the ‘potential to produce adequately modified exogenous proteins with mammalian-like post-translational modifications that may be required for their use as pharmaceutical and industrial products’. And, exploiting another major crop for human protein ends, Yang He et al. have designed rice to make human serum albumin (HAS), at levels >10% of the total soluble protein of the rice grain. Proper human-derived HSA is in short supply because of limited availability of donated blood, but is widely used in production of drugs and vaccines, and in treatment for severe burns, liver cirrhosis, and haemorrhagic shock. As the authors conclude, ‘Our results suggest that a rice seed bioreactor produces cost-effective recombinant HSA that is safe and can help to satisfy an increasing worldwide demand for human serum albumin’. Finally, news that an anti-HIV (Human Immunodeficiency Virus, which causes AIDS, Acquired ImmunoDeficiency Syndrome) antibody produced in GM tobacco underwent clinical trials in the UK in 2011. Testing was intended to establish how safely and effectively the vaginally applied product stops HIV transmission and was carried out under the watchful eyes of the UK’s Medicines and Healthcare products Agency (MHRA) at the University of Surrey Clinical Research Centre. Apparently the UK was chosen for the honour of this pharmaceutical ‘first’ because the Pharma-Plant Consortium – which is leading the trial – were put off by the level of fees required by the EMA (European Medicine Agency). So, UK vs. The Rest of Europe (c’est la vie, again…). Supporters of this whole approach to human exploitation of plants – so-called molecular farming – argue that: protein drugs could be made more efficiently and cheaply inside GM crops, since plants are extremely cost-effective protein producers; mass producing medicines in GM plants uses lower-cost tech than those of biopharmaceuticals made in huge stainless steel fermentation vats containing bacteria or mammalian cells; production costs could be 10 to 100 times lower than using conventional bioreactors; and the relatively simple manufacturing process could be transferred to developing countries. Now, surely, those fantastic plant pharma feats have got to be more impressive than getting a silkworm to spin spider silk, as reported by Florence Teulé et al.! But, if I’ve (unintentionally!) awakened in you a desire to discover more arachnoid antics, try Martin Humenik and colleague’s review of recombinant spider silks.

For both simple and compound leaves, a MYB domain transcription factor PHANTASTICA (PHAN) plays an important role in establishing the adaxial domain in the leaf. Zoulias et al.generate and analyse transgenic tomato plants expressing tomato PHAN (SlPHAN) and tobacco plants that over-express tomato SlPHAN. Modulations in SlPHAN resulted in a variety of leaf morphologies, and the results suggest that SlPHAN plays a role in medio-lateral extension of the adaxial domain and contributes to final leaf morphology in tomato.

The growth of plant cells is generally related to loosening of the cell wall, which allows cell expansion driven by osmotic water uptake. Dvorakova et al.demonstrate a correlation between over-expression of genes encoding members of the family of hybrid proline-rich proteins (HyPRPs) and enhanced elongation of tobacco BY-2 cells. The results suggest that HyPRPs, more specifically their C-terminal domains related to lipid transfer proteins, represent a novel group of proteins involved in cell-wall loosening.

Hybrid lethality is a type of postzygotic isolation and is observed in some species of Nicotiana in association with genes encoded on the Q chromosome. Tezuka et al. (pp. 267–276) make interspecific crosses of eight wild species with cultivated tobacco, N. tabacum, and find only one, N. fragrans, that produces 100 % viable hybrids. They confirm that one or more genes on the Q chromosome of N. tabacum are responsible for hybrid lethality, but the effect can be suppressed if the seedlings are grown at elevated temperatures.